The driver creates its own per-CPU threads which are updated based on
CPU hotplug events. It is also possible to delegate this task to the
smpboot-thread infrastructure and get the same job done while saving a
few lines of code.
The code checked ->thread to decide if there is an active per-CPU
thread. With the smpboot infrastructure this is no longer possible and I
replaced its logic with the ->active member. The thread pointer is saved
in `kthread' instead of `thread' so anything trying to use thread is
caught by the compiler.
The ->park() callback cleans up the resources if a CPU is going down. At
least one CPU has to be online (and not parked) and the skbs are moved to
this CPU. On module removal the ->cleanup() is invoked instead and all skbs
are purged.
The remaining part of the conversion is mostly straightforward.
This patch was only compile-tested due to -ENODEV.
Cc: Vasu Dev <vasu.dev@xxxxxxxxx>
Cc: "James E.J. Bottomley" <JBottomley@xxxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: fcoe-devel@xxxxxxxxxxxxx
Cc: linux-scsi@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 8 +-
drivers/scsi/fcoe/fcoe.c | 281 ++++++++++++++------------------------
include/scsi/libfcoe.h | 6 +-
3 files changed, 112 insertions(+), 183 deletions(-)
diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index 67405c628864..f5bc11b2e884 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -457,7 +457,7 @@ static int bnx2fc_rcv(struct sk_buff *skb, struct net_device *dev,
__skb_queue_tail(&bg->fcoe_rx_list, skb);
if (bg->fcoe_rx_list.qlen == 1)
- wake_up_process(bg->thread);
+ wake_up_process(bg->kthread);
spin_unlock(&bg->fcoe_rx_list.lock);
@@ -2654,7 +2654,7 @@ static int __init bnx2fc_mod_init(void)
}
wake_up_process(l2_thread);
spin_lock_bh(&bg->fcoe_rx_list.lock);
- bg->thread = l2_thread;
+ bg->kthread = l2_thread;
spin_unlock_bh(&bg->fcoe_rx_list.lock);
for_each_possible_cpu(cpu) {
@@ -2727,8 +2727,8 @@ static void __exit bnx2fc_mod_exit(void)
/* Destroy global thread */
bg = &bnx2fc_global;
spin_lock_bh(&bg->fcoe_rx_list.lock);
- l2_thread = bg->thread;
- bg->thread = NULL;
+ l2_thread = bg->kthread;
+ bg->kthread = NULL;
while ((skb = __skb_dequeue(&bg->fcoe_rx_list)) != NULL)
kfree_skb(skb);
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 4a877ab95d44..2bc570e96663 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -26,6 +26,7 @@
#include <linux/if_vlan.h>
#include <linux/crc32.h>
#include <linux/slab.h>
+#include <linux/smpboot.h>
#include <linux/cpu.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
@@ -80,7 +81,6 @@ static int fcoe_reset(struct Scsi_Host *);
static int fcoe_xmit(struct fc_lport *, struct fc_frame *);
static int fcoe_rcv(struct sk_buff *, struct net_device *,
struct packet_type *, struct net_device *);
-static int fcoe_percpu_receive_thread(void *);
static void fcoe_percpu_clean(struct fc_lport *);
static int fcoe_link_ok(struct fc_lport *);
@@ -107,7 +107,6 @@ static int fcoe_ddp_setup(struct fc_lport *, u16, struct scatterlist *,
static int fcoe_ddp_done(struct fc_lport *, u16);
static int fcoe_ddp_target(struct fc_lport *, u16, struct scatterlist *,
unsigned int);
-static int fcoe_cpu_callback(struct notifier_block *, unsigned long, void *);
static int fcoe_dcb_app_notification(struct notifier_block *notifier,
ulong event, void *ptr);
@@ -136,11 +135,6 @@ static struct notifier_block fcoe_notifier = {
.notifier_call = fcoe_device_notification,
};
-/* notification function for CPU hotplug events */
-static struct notifier_block fcoe_cpu_notifier = {
- .notifier_call = fcoe_cpu_callback,
-};
-
/* notification function for DCB events */
static struct notifier_block dcb_notifier = {
.notifier_call = fcoe_dcb_app_notification,
@@ -1245,55 +1239,15 @@ static int __exit fcoe_if_exit(void)
return 0;
}
-/**
- * fcoe_percpu_thread_create() - Create a receive thread for an online CPU
- * @cpu: The CPU index of the CPU to create a receive thread for
- */
-static void fcoe_percpu_thread_create(unsigned int cpu)
+static struct fcoe_percpu_s *fcoe_thread_cleanup_local(unsigned int cpu)
{
- struct fcoe_percpu_s *p;
- struct task_struct *thread;
-
- p = &per_cpu(fcoe_percpu, cpu);
-
- thread = kthread_create_on_node(fcoe_percpu_receive_thread,
- (void *)p, cpu_to_node(cpu),
- "fcoethread/%d", cpu);
-
- if (likely(!IS_ERR(thread))) {
- kthread_bind(thread, cpu);
- wake_up_process(thread);
-
- spin_lock_bh(&p->fcoe_rx_list.lock);
- p->thread = thread;
- spin_unlock_bh(&p->fcoe_rx_list.lock);
- }
-}
-
-/**
- * fcoe_percpu_thread_destroy() - Remove the receive thread of a CPU
- * @cpu: The CPU index of the CPU whose receive thread is to be destroyed
- *
- * Destroys a per-CPU Rx thread. Any pending skbs are moved to the
- * current CPU's Rx thread. If the thread being destroyed is bound to
- * the CPU processing this context the skbs will be freed.
- */
-static void fcoe_percpu_thread_destroy(unsigned int cpu)
-{
- struct fcoe_percpu_s *p;
- struct task_struct *thread;
struct page *crc_eof;
- struct sk_buff *skb;
- struct fcoe_percpu_s *p_target;
- unsigned targ_cpu = get_cpu();
-
- FCOE_DBG("Destroying receive thread for CPU %d\n", cpu);
+ struct fcoe_percpu_s *p;
/* Prevent any new skbs from being queued for this CPU. */
- p = &per_cpu(fcoe_percpu, cpu);
+ p = per_cpu_ptr(&fcoe_percpu, cpu);
spin_lock_bh(&p->fcoe_rx_list.lock);
- thread = p->thread;
- p->thread = NULL;
+ p->active = false;
crc_eof = p->crc_eof_page;
p->crc_eof_page = NULL;
p->crc_eof_offset = 0;
@@ -1301,81 +1255,56 @@ static void fcoe_percpu_thread_destroy(unsigned int cpu)
if (crc_eof)
put_page(crc_eof);
- /*
- * Don't bother moving the skb's if this context is running
- * on the same CPU that is having its thread destroyed. This
- * can easily happen when the module is removed.
- */
- if (cpu != targ_cpu) {
- p_target = &per_cpu(fcoe_percpu, targ_cpu);
- spin_lock_bh(&p_target->fcoe_rx_list.lock);
- if (p_target->thread) {
- FCOE_DBG("Moving frames from CPU %d to CPU %d\n",
- cpu, targ_cpu);
-
- skb_queue_splice_tail(&p->fcoe_rx_list,
- &p_target->fcoe_rx_list);
- spin_unlock_bh(&p_target->fcoe_rx_list.lock);
- } else {
- /*
- * The targeted CPU is not initialized and cannot accept
- * new skbs. Unlock the targeted CPU and drop the skbs
- * on the CPU that is going offline.
- */
- spin_unlock_bh(&p_target->fcoe_rx_list.lock);
-
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
- kfree_skb(skb);
- }
- } else {
- /*
- * This scenario occurs when the module is being removed
- * and all threads are being destroyed. skbs will continue
- * to be shifted from the CPU thread that is being removed
- * to the CPU thread associated with the CPU that is processing
- * the module removal. Once there is only one CPU Rx thread it
- * will reach this case and we will drop all skbs and later
- * stop the thread.
- */
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) != NULL)
- kfree_skb(skb);
- }
- put_cpu();
-
- if (thread)
- kthread_stop(thread);
+ return p;
}
/**
- * fcoe_cpu_callback() - Handler for CPU hotplug events
- * @nfb: The callback data block
- * @action: The event triggering the callback
- * @hcpu: The index of the CPU that the event is for
+ * fcoe_thread_park() - Park the receive thread of a CPU
+ * @cpu: The CPU index of the CPU whose receive thread is to be parked
*
- * This creates or destroys per-CPU data for fcoe
- *
- * Returns NOTIFY_OK always.
+ * Parks the per-CPU Rx thread. Any pending skbs are moved to the
+ * first online CPU's Rx thread.
*/
-static int fcoe_cpu_callback(struct notifier_block *nfb,
- unsigned long action, void *hcpu)
+static void fcoe_thread_park(unsigned int cpu)
{
- unsigned cpu = (unsigned long)hcpu;
+ struct fcoe_percpu_s *p;
+ struct fcoe_percpu_s *p_target;
+ unsigned int targ_cpu = cpumask_any_but(cpu_online_mask, cpu);
- switch (action) {
- case CPU_ONLINE:
- case CPU_ONLINE_FROZEN:
- FCOE_DBG("CPU %x online: Create Rx thread\n", cpu);
- fcoe_percpu_thread_create(cpu);
- break;
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- FCOE_DBG("CPU %x offline: Remove Rx thread\n", cpu);
- fcoe_percpu_thread_destroy(cpu);
- break;
- default:
- break;
- }
- return NOTIFY_OK;
+ FCOE_DBG("Parking receive thread for CPU %d\n", cpu);
+
+ p = fcoe_thread_cleanup_local(cpu);
+
+ p_target = &per_cpu(fcoe_percpu, targ_cpu);
+ spin_lock_bh(&p_target->fcoe_rx_list.lock);
+ BUG_ON(!p_target->active);
+ FCOE_DBG("Moving frames from CPU %u to CPU %u\n", cpu, targ_cpu);
+
+ skb_queue_splice_tail(&p->fcoe_rx_list,
+ &p_target->fcoe_rx_list);
+ spin_unlock_bh(&p_target->fcoe_rx_list.lock);
+}
+
+/**
+ * fcoe_thread_cleanup() - Cleanup the receive thread of a CPU
+ * @cpu: The CPU index of the CPU whose receive thread is to be cleaned up
+ * @online: true if the CPU is still online.
+ *
+ * Cleans up the per-CPU Rx thread. Any pending skbs are freed because this
+ * module will be removed. If the CPU is not online then it was parked and
+ * there are not resources bound to this per-CPU structure.
+ */
+static void fcoe_thread_cleanup(unsigned int cpu, bool online)
+{
+ struct fcoe_percpu_s *p;
+ struct sk_buff *skb;
+
+ if (!online)
+ return;
+ p = fcoe_thread_cleanup_local(cpu);
+
+ while ((skb = __skb_dequeue(&p->fcoe_rx_list)))
+ kfree_skb(skb);
}
/**
@@ -1494,7 +1423,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
fps = &per_cpu(fcoe_percpu, cpu);
spin_lock(&fps->fcoe_rx_list.lock);
- if (unlikely(!fps->thread)) {
+ if (unlikely(!fps->active)) {
/*
* The targeted CPU is not ready, let's target
* the first CPU now. For non-SMP systems this
@@ -1508,7 +1437,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
cpu = cpumask_first(cpu_online_mask);
fps = &per_cpu(fcoe_percpu, cpu);
spin_lock(&fps->fcoe_rx_list.lock);
- if (!fps->thread) {
+ if (!fps->active) {
spin_unlock(&fps->fcoe_rx_list.lock);
goto err;
}
@@ -1528,8 +1457,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
* in softirq context.
*/
__skb_queue_tail(&fps->fcoe_rx_list, skb);
- if (fps->thread->state == TASK_INTERRUPTIBLE)
- wake_up_process(fps->thread);
+ wake_up_process(per_cpu_ptr(fcoe_percpu.kthread, cpu));
spin_unlock(&fps->fcoe_rx_list.lock);
return NET_RX_SUCCESS;
@@ -1842,40 +1770,42 @@ static void fcoe_recv_frame(struct sk_buff *skb)
}
/**
- * fcoe_percpu_receive_thread() - The per-CPU packet receive thread
- * @arg: The per-CPU context
+ * fcoe_thread_receive() - The per-CPU packet receive thread
+ * @arg: The CPU number
*
- * Return: 0 for success
*/
-static int fcoe_percpu_receive_thread(void *arg)
+static void fcoe_thread_receive(unsigned int cpu)
{
- struct fcoe_percpu_s *p = arg;
+ struct fcoe_percpu_s *p = per_cpu_ptr(&fcoe_percpu, cpu);
struct sk_buff *skb;
struct sk_buff_head tmp;
skb_queue_head_init(&tmp);
- set_user_nice(current, MIN_NICE);
+ spin_lock_bh(&p->fcoe_rx_list.lock);
+ skb_queue_splice_init(&p->fcoe_rx_list, &tmp);
+ spin_unlock_bh(&p->fcoe_rx_list.lock);
- while (!kthread_should_stop()) {
+ if (!skb_queue_len(&tmp))
+ return;
- spin_lock_bh(&p->fcoe_rx_list.lock);
- skb_queue_splice_init(&p->fcoe_rx_list, &tmp);
+ while ((skb = __skb_dequeue(&tmp)))
+ fcoe_recv_frame(skb);
- if (!skb_queue_len(&tmp)) {
- set_current_state(TASK_INTERRUPTIBLE);
- spin_unlock_bh(&p->fcoe_rx_list.lock);
- schedule();
- continue;
- }
+ return;
+}
- spin_unlock_bh(&p->fcoe_rx_list.lock);
+static int fcoe_thread_should_run(unsigned int cpu)
+{
+ struct fcoe_percpu_s *p = per_cpu_ptr(&fcoe_percpu, cpu);
- while ((skb = __skb_dequeue(&tmp)) != NULL)
- fcoe_recv_frame(skb);
-
- }
- return 0;
+ /*
+ * Lockless peek on the list to see if it is empty. Real check happens
+ * in fcoe_thread_receive().
+ */
+ if (skb_queue_empty(&p->fcoe_rx_list))
+ return 0;
+ return 1;
}
/**
@@ -2459,7 +2389,7 @@ static void fcoe_percpu_clean(struct fc_lport *lport)
spin_lock_bh(&pp->fcoe_rx_list.lock);
__skb_queue_tail(&pp->fcoe_rx_list, skb);
if (pp->fcoe_rx_list.qlen == 1)
- wake_up_process(pp->thread);
+ wake_up_process(per_cpu_ptr(fcoe_percpu.kthread, cpu));
spin_unlock_bh(&pp->fcoe_rx_list.lock);
wait_for_completion(&fcoe_flush_completion);
@@ -2583,6 +2513,32 @@ static struct fcoe_transport fcoe_sw_transport = {
.disable = fcoe_disable,
};
+static void fcoe_thread_setup(unsigned int cpu)
+{
+ struct fcoe_percpu_s *p = per_cpu_ptr(&fcoe_percpu, cpu);
+
+ set_user_nice(current, MIN_NICE);
+ skb_queue_head_init(&p->fcoe_rx_list);
+}
+
+static void fcoe_thread_unpark(unsigned int cpu)
+{
+ struct fcoe_percpu_s *p = per_cpu_ptr(&fcoe_percpu, cpu);
+
+ p->active = true;
+}
+
+static struct smp_hotplug_thread fcoe_threads = {
+ .store = &fcoe_percpu.kthread,
+ .setup = fcoe_thread_setup,
+ .cleanup = fcoe_thread_cleanup,
+ .thread_should_run = fcoe_thread_should_run,
+ .thread_fn = fcoe_thread_receive,
+ .park = fcoe_thread_park,
+ .unpark = fcoe_thread_unpark,
+ .thread_comm = "fcoethread/%u",
+};
+
/**
* fcoe_init() - Initialize fcoe.ko
*
@@ -2590,8 +2546,6 @@ static struct fcoe_transport fcoe_sw_transport = {
*/
static int __init fcoe_init(void)
{
- struct fcoe_percpu_s *p;
- unsigned int cpu;
int rc = 0;
fcoe_wq = alloc_workqueue("fcoe", 0, 0);
@@ -2608,22 +2562,7 @@ static int __init fcoe_init(void)
mutex_lock(&fcoe_config_mutex);
- for_each_possible_cpu(cpu) {
- p = &per_cpu(fcoe_percpu, cpu);
- skb_queue_head_init(&p->fcoe_rx_list);
- }
-
- cpu_notifier_register_begin();
-
- for_each_online_cpu(cpu)
- fcoe_percpu_thread_create(cpu);
-
- /* Initialize per CPU interrupt thread */
- rc = __register_hotcpu_notifier(&fcoe_cpu_notifier);
- if (rc)
- goto out_free;
-
- cpu_notifier_register_done();
+ smpboot_register_percpu_thread(&fcoe_threads);
/* Setup link change notification */
fcoe_dev_setup();
@@ -2636,11 +2575,7 @@ static int __init fcoe_init(void)
return 0;
out_free:
- for_each_online_cpu(cpu) {
- fcoe_percpu_thread_destroy(cpu);
- }
-
- cpu_notifier_register_done();
+ smpboot_unregister_percpu_thread(&fcoe_threads);
mutex_unlock(&fcoe_config_mutex);
destroy_workqueue(fcoe_wq);
@@ -2658,7 +2593,6 @@ static void __exit fcoe_exit(void)
struct fcoe_interface *fcoe, *tmp;
struct fcoe_ctlr *ctlr;
struct fcoe_port *port;
- unsigned int cpu;
mutex_lock(&fcoe_config_mutex);
@@ -2674,14 +2608,7 @@ static void __exit fcoe_exit(void)
}
rtnl_unlock();
- cpu_notifier_register_begin();
-
- for_each_online_cpu(cpu)
- fcoe_percpu_thread_destroy(cpu);
-
- __unregister_hotcpu_notifier(&fcoe_cpu_notifier);
-
- cpu_notifier_register_done();
+ smpboot_unregister_percpu_thread(&fcoe_threads);
mutex_unlock(&fcoe_config_mutex);
diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
index de7e3ee60f0c..74ea1ea9c1f6 100644
--- a/include/scsi/libfcoe.h
+++ b/include/scsi/libfcoe.h
@@ -319,17 +319,19 @@ struct fcoe_transport {
/**
* struct fcoe_percpu_s - The context for FCoE receive thread(s)
- * @thread: The thread context
+ * @kthread: The thread context of the smp_hotplug_thread
* @fcoe_rx_list: The queue of pending packets to process
* @page: The memory page for calculating frame trailer CRCs
* @crc_eof_offset: The offset into the CRC page pointing to available
* memory for a new trailer
+ * @active: true if the queue is active and not being removed
*/
struct fcoe_percpu_s {
- struct task_struct *thread;
+ struct task_struct *kthread;
struct sk_buff_head fcoe_rx_list;
struct page *crc_eof_page;
int crc_eof_offset;
+ bool active;
};
/**
--
2.7.0
--
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